I can tell I’ve got a bona-fide rock star in the back of my cab because Adam Levine, frontman of exuberant Californian pop-rock band Maroon 5, refuses to take off his dark glasses for his photo shoot. But he does give me a glimpse of himself naked from the nose up so that I can check out the irises of the man who sings such great ‘blue-eyed soul’.

‘They’re usually a green colour – but today they’re red because I’m so knackered from the flight,’ says Los Angeles-based Adam, slowly lowering his shades with all the tantalising expertise of a stripper shedding her feather boa.

With such an instinct for delayed gratification, it’s no wonder there’s a huge female fanbase for the band whose 2002 debut album Songs About Jane, inspired by Adam’s former girlfriend, sold more than ten million copies. Their video for the song ‘This Love’ featured a sexy horizontal writhe between Adam and his then girlfriend, model Kelly McKee, and the latest single is a provocative battle-of-the-sexes duet with the gorgeous Rihanna. ‘She was amazing – we had a lot of chemistry. Much of our music is sexually driven, because I love women,’ says Adam, 29.

Our cabbie, Richard from Hornchurch, drives us past Adam’s favourite West End haunt, Savile Row. ‘I’m not very spruced up at the moment – we’ve been on a tour bus for too long,’ explains this designer-loving dude who wears suits on stage. He’s dressed down by his standards in black leather jacket over jeans and Yves Saint Laurent boots.

Three of the band – singer, rhythm guitarist and main songwriter Adam, jazz-trained keyboardist Jesse Carmichael and bassist Mickey Madden – first met at Hollywood’s Brentwood High School, with drummer Matt Flynn and lead guitarist James Valentine joining later.

Their second album, It Won’t Be Soon Before Long, set a new record for iTunes in 2007 by selling half a million copies in the first week of release. Thank God they dropped the uncool name of Kara’s Flowers, though their choice of Maroon 5 continues to baffle.

‘We held a ritual under a Joshua tree and drank peyote [a Mexican liquor] and took a vow never to reveal the origin,’ says Adam melodramatically, adding, ‘Only Billy Joel knows.’ Who says Americans don’t do irony?

‘It’s flattering, but although I actually dated some of them, I’ve never even met the others. Until I’m married, I’m going to keep my private life quiet. I would like to be with somebody for ever, but marriage is a failed institution statistically, which is kind of disheartening,’ says Adam, whose parents split up when he was seven. ‘I don’t know if it’s possible to live the rock’n’roll lifestyle and still be romantic, but I think long, deep relationships are amazing.’

Yet one relationship that won’t last, he hints, is with his band. ‘I’ve spent my 20s on tour and there’s no consistency in my life, which can take its toll,’ says Adam. ‘Eventually I want to focus on being a completely different person because I don’t know if I want to do this into my 40s and 50s and beyond, like the Rolling Stones.’

Yet he couldn’t help being impressed by what a ‘regular guy’ Mick Jagger was when they supported the Stones and were invited into Mick’s dressing room. ‘He was just watching football and putting on his shoes, which made me realise how mythical all those stories are about the Stones being a larger-than-life entity. People deify people. But as John Lennon said, “We’re just a band playing songs” – even though the Beatles were the greatest band that ever walked,’ says Adam, who grew up on his baby-boomer parents’ record collection.

‘I don’t want to give it up just yet, though – I think we have a little more to say.’ And long may he say it.

Maroon 5’s new single ‘If I Never See Your Face Again’ is out on A&M’s Octone label